Compositions for dark-field polymerization and method of using the same for imprint lithography processes

ABSTRACT

The present invention provides a composition and a method of using the same to form a pattern on a substrate using imprint lithography employing dark-field polymerization. To that end, the composition includes a bis vinyl ether component, and an initiator component that produces an acid in response to radiation. The bis vinyl ether component is reactive to the acid and polymerizes in response thereto.

BACKGROUND OF THE INVENTION

[0001] The field of invention relates generally to micro-fabrication ofstructures. More particularly, the present invention is directed topatterning substrates in furtherance of the formation of structures.

[0002] Micro-fabrication involves the fabrication of very smallstructures, e.g., having features on the order of micro-meters orsmaller. One area in which micro-fabrication has had a sizeable impactis in the processing of integrated circuits. As the semiconductorprocessing industry continues to strive for larger production yieldswhile increasing the circuits per unit area formed on a substrate,micro-fabrication becomes increasingly important. Micro-fabricationprovides greater process control while allowing reduction of the minimumfeature dimension of the structures formed. Other areas of developmentin which micro-fabrication has been employed include biotechnology,optical technology, mechanical systems and the like.

[0003] An exemplary micro-fabrication technique is shown in U.S. Pat.No. 6,334,960 to Willson et al. Willson et al. disclose a method offorming a relief image in a structure. The method includes providing asubstrate having a transfer layer. The transfer layer is covered with apolymerizable fluid composition. A mold makes mechanical contact withthe polymerizable fluid. The mold includes a relief structure, and thepolymerizable fluid composition fills the relief structure. Thepolymerizable fluid composition is then subjected to conditions tosolidify and polymerize the same, forming a solidified polymericmaterial on the transfer layer that contains a relief structurecomplimentary to that of the mold. The mold is then separated from thesolidified polymeric material such that a replica of the reliefstructure in the mold is formed in the solidified polymeric material.The transfer layer and the solidified polymeric material are subjectedto an environment to selectively etch the transfer layer relative to thesolidified polymeric material such that a relief image is formed in thetransfer layer. The time required and the minimum feature dimensionprovided by this technique is dependent upon, inter alia, thecomposition of the polymerizable material.

[0004] It is desired, therefore, to provide improved compositions ofpolymerizable materials for use in micro-fabrication.

SUMMARY OF THE INVENTION

[0005] The present invention is directed toward a composition and methodof using the same to form a pattern on a substrate employing imprintlithography employing dark-field polymerization. To that end, thecomposition includes a bis vinyl ether component, and an initiatorcomponent that produces an acid in response to radiation. The bis vinylether component is reactive to the acid and polymerizes in responsethereto. The method includes forming a layer of polymerizable materialon the substrate, and contacting the layer of polymerizable materialwith a surface of a mold to conform the layer to the surface. Partialpolymerization of the layer is achieved by impinging radiation thereuponand terminating the radiation before polymerization of the polymerizablematerial is complete. The mold is separated from the layer beforecomplete polymerization of the layer occurs. Complete polymerization ofthe layer occurs by allowing the acid from the initiator to react withthe layer to form a solidified layer of the polymerizable material.These and other embodiments are discussed more fully below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006]FIG. 1 is a simplified elevation view of a lithographic system inaccordance with the present invention;

[0007]FIG. 2 is a simplified representation of material from which animprinting layer, shown in FIG. 1, is comprised before being polymerizedand cross-linked;

[0008]FIG. 3 is a simplified representation of cross-linked polymermaterial into which the material shown in FIG. 2 is transformed afterbeing subjected to radiation;

[0009]FIG. 4 is a simplified elevation view of an imprint device, shownin FIG. 1, in mechanical contact with an imprint layer disposed on asubstrate, in accordance with one embodiment of the present invention;

[0010]FIG. 5 is a simplified elevation view of the imprint devicespaced-apart from the imprint layer, shown in FIG. 4, after patterningof the imprint layer;

[0011]FIG. 6 is a simplified elevation view of the imprint device andimprint layer shown in FIG. 5, with residue remaining in the pattern;

[0012]FIG. 7 is a flow diagram showing polymerization employing darkfield polymerization in accordance with one embodiment of the presentinvention; and

[0013]FIG. 8 is a simplified elevation view of material in an imprintdevice and substrate employed with the present invention in accordancewith an alternate embodiment.

DETAILED DESCRIPTION OF THE INVENTION

[0014] Referring to FIG. 1, a lithographic system in accordance with anembodiment of the present invention includes a substrate 10, having asubstantially planar region shown as surface 12. Disposed oppositesubstrate 10 is an imprint device 14 having a plurality of featuresthereon, forming a plurality of spaced-apart recesses 16 and protrusions18. In the present embodiment, the recesses 16 are a plurality ofgrooves extending along a direction parallel to protrusions 18 thatprovide a cross-section of imprint device 14 with a shape of abattlement. However, the recesses 16 may correspond to virtually anyfeature required to create an integrated circuit. A translationmechanism 20 is connected between imprint device 14 and substrate 10 tovary a distance “d” between imprint device 14 and substrate 10. Aradiation source 22 is located so that imprint device 14 is positionedbetween radiation source 22 and substrate 10. Radiation source 22 isconfigured to impinge radiation on substrate 10. To realize this,imprint device 14 is fabricated from material that allows it to besubstantially transparent to the radiation produced by radiation source22.

[0015] Referring to both FIGS. 1 and 2, an imprinting layer 24 isdisposed adjacent to surface 12, between substrate 10 and imprint device14. Although imprinting layer 24 may be deposited using any knowntechnique, in the present embodiment, imprinting layer 24 is depositedas a plurality of spaced-apart discrete beads 25 of material 25 a onsubstrate 10, discussed more fully below. Imprinting layer 24 is formedfrom a material 25 a that may be selectively polymerized andcross-linked to record a desired pattern. Material 25 a is shown in FIG.3 as being cross-linked at points 25 b, forming cross-linked polymermaterial 25 c.

[0016] Referring to both FIGS. 1 and 4, the pattern recorded byimprinting layer 24 is produced, in part, by mechanical contact withimprint device 14. To that end, translation mechanism 20 reduces thedistance “d” to allow imprinting layer 24 to come into mechanicalcontact with imprint device 14, spreading beads 25 so as to formimprinting layer 24 with a contiguous formation of material 25 a oversurface 12. In one embodiment, distance “d” is reduced to allowsub-portions 24 a of imprinting layer 24 to ingress into and fillrecesses 16.

[0017] Referring to FIGS. 1, 2 and 4, to facilitate filling of recesses16, material 25 a is provided with the requisite viscosity to completelyfill recesses 16 in a timely manner, while covering surface 12 with acontiguous formation of material 25 a, on the order of a fewmilliseconds to a few seconds. In the present embodiment, sub-portions24 b of imprinting layer 24 in superimposition with protrusions 18remain after the desired, usually minimum distance “d” has reached aminimum distance, leaving sub-portions 24 a with a thickness t₁, andsub-portions 24 b with a thickness, t₂. Thicknesses “t₁” and “t₂” may beany thickness desired, dependent upon the application. Further, inanother embodiment, sub-portions 24 b may be abrogated entirely wherebythe only remaining material from imprinting layer 24 are sub-portions 24a, after distance, “d” has reached a minimum value.

[0018] Referring to FIGS. 1, 2 and 3, after a desired distance “d” hasbeen reached, radiation source 22 produces actinic radiation thatpolymerizes and cross-links material 25 a, forming cross-linked polymermaterial 25 c. As a result, the composition of imprinting layer 24transforms from material 25 a to material 25 c, which is a solid.Specifically, material 25 c is solidified to provide surface 24 c ofimprinting layer 24 with a shape conforming to a shape of a surface 14 aof imprint device 14, shown more clearly in FIG. 5.

[0019] Referring to FIGS. 1, 2 and 3 an exemplary radiation source 22may produce ultraviolet radiation. Other radiation sources may beemployed, such as thermal, electromagnetic and the like. The selectionof radiation employed to initiate the polymerization of the material inimprinting layer 24 is known to one skilled in the art and typicallydepends on the specific application which is desired. After imprintinglayer 24 is transformed to consist of material 25 c, translationmechanism 20 increases the distance “d” so that imprint device 14 andimprinting layer 24 are spaced-apart.

[0020] Referring to FIG. 5, additional processing may be employed tocomplete the patterning of substrate 10. For example, substrate 10 andimprinting layer 24 may be selectively etched to increase the aspectratio of recesses 30 in imprinting layer 24. To facilitate etching, thematerial from which imprinting layer 24 is formed may be varied todefine a relative etch rate with respect to substrate 10, as desired.The relative etch rate of imprinting layer 24 to substrate 10 may be ina range of about 1.5:1 to about 100:1. Alternatively, or in addition to,imprinting layer 24 may be provided with an etch differential withrespect to photo-resist material (not shown) selectively disposed onsurface 24 c. The photo-resist material (not shown) may be provided tofurther pattern imprinting layer 24, using known techniques. Any etchprocess may be employed, dependent upon the etch rate desired and theunderlying constituents that form substrate 10 and imprinting layer 24.Exemplary etch processes may include plasma etching, reactive ionetching and the like.

[0021] Referring to FIGS. 2, 3 and 6, residual material 26 may bepresent on imprinting layer 24 after patterning has been completed.Residual material 26 may consist of un-polymerized material 25 a, solidpolymerized and cross-linked material 25 c, substrate 10 or acombination thereof. Further processing may be included to removeresidual material 26 using well known techniques, e.g., argon ionmilling, a plasma etch, reactive ion etching or a combination thereof.Further, removal of residual material 26 may be accomplished during anystage of the patterning. For example, removal of residual material 26may be carried out before etching the polymerized and cross-linkedimprinting layer 24.

[0022] Referring to FIGS. 1 and 5, the aspect ratio of recesses 30formed from the aforementioned patterning technique may be as great as30:1. To that end, one embodiment of imprint device 14 has recesses 16defining an aspect ratio in a range of 1:1 to 10:1. Specifically,protrusions 18 have a width W₁ in a range of about 10 nm to about 5000μm, and recesses 16 have a width W₂ in a range of 10 nm to about 5000μm. As a result, imprint device 14 may be formed from variousconventional materials, such as, but not limited to, quartz, silicon,organic polymers, siloxane polymers, borosilicate glass, fluorocarbonpolymers, metal, and combinations of the above.

[0023] Referring to FIGS. 1 and 2, the characteristics of material 25 aare important to efficiently pattern substrate 10 in light of the uniquedeposition process employed. As mentioned above, material 25 a isdeposited on substrate 10 as a plurality of discrete and spaced-apartbeads 25. The combined volume of beads 25 is such that the material 25 ais distributed appropriately over area of surface 12 where imprintinglayer 24 is to be formed. As a result, imprinting layer 24 is spread andpatterned concurrently, with the pattern being subsequently set byexposure to radiation, such as ultraviolet radiation. As a result of thedeposition process it is desired that material 25 a have certaincharacteristics to facilitate rapid and even spreading of material 25 ain beads 25 over surface 12 so that the all thicknesses t₁ aresubstantially uniform and all thickness t₂ are substantially uniform.The desirable characteristics include having a viscosity approximatelythat of water, (H₂0), 1 to 2 centepoise (csp), or less, as well as theability to wet surface of substrate 10 to avoid subsequent pit or holeformation after polymerization. To that end, in one example, thewettability of imprinting layer 24, as defined by the contact anglemethod, should be such that the angle, θ₁, is defined as follows:

0≧θ₁<75°

[0024] With these two characteristics being satisfied, imprinting layer24 may be made sufficiently thin while avoiding formation of pits orholes in the thinner regions, such as sub-portions 24 b, shown in FIG.4.

[0025] Referring to FIGS. 2, 3 and 5, another desirable characteristicthat it is desired for material 25 a to possess is thermal stabilitysuch that the variation in an angle Φ, measured between a nadir 30 a ofa recess 30 and a sidewall 30 b thereof, does not vary more than 10%after being heated to 75° C. for thirty (30) minutes. Additionally,material 25 a should transform to material 25 c, i.e., polymerize andcross-link, when subjected to a pulse of radiation containing less than5 J cm-2. In the present example, polymerization and cross-linking wasdetermined by analyzing the infrared absorption of the “C═C” bondcontained in material 25 a. Additionally, it is desired that substratesurface 12 be relatively inert toward material 25 a, such that less than500 nm of surface 12 be dissolved as a result sixty seconds of contactwith material 25 a. It is further desired that the wetting of imprintdevice 14 by imprinting layer 24 be minimized. To that end, the wettingangle, θ₂, should be greater than 75°. Finally, should it be desired tovary an etch rate differential between imprinting layer 24 and substrate10, an exemplary embodiment of the present invention would demonstratean etch rate that is 20% less than the etch rate of an opticalphoto-resist (not shown) exposed to an oxygen plasma.

[0026] The constituent components that form material 25 a to provide theaforementioned characteristics may differ. This results from substrate10 being formed from a number of different materials. As a result, thechemical composition of surface 12 varies dependent upon the materialfrom which substrate 10 is formed. For example, substrate 10 may beformed from silicon, plastics, gallium arsenide, mercury telluride, andcomposites thereof. Additionally, substrate may include one or morelayers in region, e.g., dielectric layer, metal layers, semiconductorlayer and the like.

[0027] Referring to FIGS. 2 and 3, in one embodiment of the presentinvention the constituent components of material 25 a consist ofacrylated monomers or methacrylated monomers that are not silyated, across-linking agent, and an initiator. The non-silyated acryl ormethacryl monomers are selected to provide material 25 a with a minimalviscosity, e.g., viscosity approximating the viscosity of water (1-2cps) or less. The cross-linking agent is included, even though the sizeof these molecules increases the viscosity of material 25 a, tocross-link the molecules of the non-silyated monomers, providingmaterial 25 a with the properties to record a pattern thereon havingvery small feature sizes, on the order of a few nanometers and toprovide the aforementioned thermal stability for further processing. Tothat end, the initiator is provided to produce a free radical reactionin response to radiation, causing the non-silyated monomers and thecross-linking agent to polymerize and cross-link, forming a cross-linkedpolymer material 25 c. In the present example, a photo-initiatorresponsive to ultraviolet radiation is employed. In addition, ifdesired, a silyated monomer may also be included in material 25 a tocontrol the etch rate of the resulting cross-linked polymer material 25c, without substantially affecting the viscosity of material 25 a.

[0028] Examples of non-silyated monomers include, but are not limitedto, butyl acrylate, methyl acrylate, methyl methacrylate, or mixturesthereof. The non-silyated monomer may make up approximately 25 to 60% byweight of material 25 a. It is believed that the monomer providesadhesion to an underlying organic transfer layer, discussed more fullybelow.

[0029] The cross-linking agent is a monomer that includes two or morepolymerizable groups. In one embodiment, polyfunctional siloxanederivatives may be used as a cross-linking agent. An example of apolyfunctional siloxane derivative is1,3-bis(3-methacryloxypropyl)-tetramethyl disiloxane. Another suitablecross-linking agent consists of ethylene diol diacrylate. Thecross-linking agent may be present in material 25 a in amounts of up to20% by weight, but is more typically present in an amount of 5 to 15% byweight.

[0030] The initiator may be any component that initiates a free radicalreaction in response to radiation, produced by radiation source 22,impinging thereupon and being absorbed thereby. Suitable initiators mayinclude, but are not limited to, photo-initiators such as1-hydroxycyclohexyl phenyl ketone or phenylbis(2,4,6-trimethyl benzoyl)phosphine oxide. The initiator may be present in material 25 a inamounts of up to 5% by weight, but is typically present in an amount of1 to 4% by weight.

[0031] Were it desired to include silylated monomers in material 25 a,suitable silylated monomers may include, but are not limited to,silyl-acryloxy and silyl methacryloxy derivatives. Specific examples aremethacryloxypropyl tris(tri-methylsiloxy)silane and(3-acryloxypropyl)tris(tri-methoxysiloxy)-silane. Silylated monomers maybe present in material 25 a in amounts from 25 to 50% by weight. Thecurable liquid may also include a dimethyl siloxane derivative. Examplesof dimethyl siloxane derivatives include, but are not limited to,(acryloxypropyl) methylsiloxane dimethylsiloxane copolymer.

[0032] Referring to both FIGS. 1 and 2, exemplary compositions formaterial 25 a are as follows:

COMPOSITION 1 n-butylacrylate+(3-acryloxypropyltristrimethylsiloxy)silane+1,3-bis(3-methacryloxypropyl)tetramethyldisiloxaneCOMPOSITION 2 t-n-butylacrylate+(3-acryloxypropyltristrimethylsiloxy)silane+Ethylene dioldiacrylate COMPOSITION 3 t-butylacrylate+methacryloxypropylpentamethyldisiloxane+1,3-bis(3-methacryloxypropyl)tetramethyldisiloxane

[0033] The above-identified compositions also include stabilizers thatare well known in the chemical art to increase the operational life, aswell as initiators.

[0034] Referring to both FIGS. 1 and 7, another class of compositionsthat have shown promise for use as imprinting layer 24 is siliconcontaining (bis) vinyl ethers. Silicon-containing (bis) vinyl ethershave demonstrated the suitable properties of viscosity and wetting,discussed above. Other advantages, however, are provided bysilicon-containing (bis) vinyl ethers. By including a suitableinitiator, silicon-containing (bis) vinyl ethers may polymerize underdark conditions, i.e., in the absence of actinic radiation, such as UVlight. For example, a mixture of (bis) vinyl ethers and acid facilitatespolymerization in the presence of air. Specifically, exposing themixture of (bis) vinyl ethers and a material capable of releasing acidwhen exposed to actinic, such as UV light, facilitates polymerization ofthe (bis) vinyl ether. Examples of such acid-producing materialsinclude, but are not limited to triphenylsulphonium salts anddiphenyliodonium salts with the following counter-ions: antimonyhexafluoride; phosphorus hexafluoride; boron tetrafluoride; tris(trifluoromethylsulphonyl) methide. In an example of such a composition,the exposure of the mixture of (bis) vinyl ethers and diphenyl-iodoniumtris(trifluoromethylsulphonyl) methide (referred hereafter asdiaryl-iodonium methide) need only be for a short amount of time toinitiate polymerization. Complete polymerization of (bis) vinyl ethersmay occur in the presence of air. Specifically, once exposure to the UVlight has terminated, acid production by diaryl-iodonium methidecontinues to facilitate complete polymerization of the (bis) vinyl etherin the absence of UV light. As a result, the time required to polymerizethe same by exposure to actinic radiation, such as UV light, may besubstantially reduced. This greatly increases through-put. Exemplarysilicon-containing (bis) vinyl ethers that may be employed to formimprinting layer 24 include bis(vinyloxymethyl)dimethysilane andbis(divinyloxymethyl)tetramethyldisiloxane. An exemplary mixture of(bis)vinyl ethers may include 25 diaryl-iodonium methide initiator withthe remaining portion being either bis(vinyloxymethyl)dimethysilane orbis(divinyloxymethyl)tetramethyldisiloxane, and a few parts per millionof a base. The base reduces the probability of unwanted acid productionby the diaryl-iodonium methide initiator. It is also possible, to createother mixtures to obtain a desired viscosity. For example,bis(vinyloxymethyl)dimethysilane orbis(divinyloxymethyl)tetramethyldisiloxane may be mixed with a monomer,such as ethylene glycol divinyl ether, as well as the diaryl iodoniummethide and base. This also forms a suitable material for use in formingimprinting layer 24.

[0035] Taking advantage of properties of the silicon-containing (bis)vinyl ethers a method of imprinting includes depositing a polymerizablelayer including silicon-containing (bis) vinyl ethers upon substrate 10to form imprinting layer 24, at step 100. Imprint device 14 is broughtinto mechanical contact with imprinting layer 24 to record the patternthereon, at step 102. After imprint device 14 is brought into contactwith imprinting layer 24, bright-field polymerization occurs by exposingimprinting layer 24 to actinic radiation, at step 104. To increase thethroughput of the process the bright-field polymerization achieves onlypartial polymerization. As a result bright-field polymerization occursfor the minimum time required to ensure that the pattern recorded inimprint layer 24 is sufficient to maintain a stable pattern when imprintdevice 14 is separated from imprinting layer 24, at step 106. The timeduring which bright-field polymerization takes place is dependent upon,inter alia, the feature size in the pattern, the thickness of imprintinglayer 24, radiation intensity, as well as environmental conditions.Polymerization is then completed employing dark-field polymerization, atstep 108. Thereafter, subsequent processing steps may take place, asdiscussed above.

[0036] Referring to FIGS. 2 and 8, employing the compositions describedabove in material 25 a to facilitate imprint lithography was achieved bydefining a surface 112 of substrate 110 with a planarization layer 32disposed adjacent to a wafer 33. The primary function of planarizationlayer 32 is to ensure surface 112 is planar. To that end, planarizationlayer 32 may be formed from a number of differing materials, such as,for example, thermoset polymers, thermoplastic polymers, polyepoxies,polyamides, polyurethanes, polycarbonates, polyesters, and combinationsthereof. It is desired that planarization layer 32 be formed frommaterial that polymerizes, or cures, in response to the actinicradiation employed to cure imprint layer 24 and adheres well thereto andother adjacent layers and experiences less than 15% shrinkage duringcuring. Planarization layer 32 should not substantially penetrateimprinting layer 24. Specifically, it is desired that planarizationlayer 32 not swell to the extent where there is more than 5% ofplanarization layer 32 penetrating imprinting layer 24. Additionally, itis desired that the material have a viscosity of less than 5 cps andmore particularly less than 2 cps at 20° C. A class of material thatdemonstrates these characteristics is non-silicon-containing acrylates.An exemplary material is ethylene glycol diacrylate combined with aninitiator and stabilizers for long shelf life. The initiator, may be anyof those discussed above and is responsive to actinic radiation, such asUV light and causes a free radical which facilitates polymerization andcross-linking of the ethylene glycol acrylate. Typically, the initiatordoes not constitute more than 5% of the mixture.

[0037] Employing ethylene glycol diacrylate, planarization layer 32 isfabricated in a manner similar to imprinting layer 24 using afeatureless mold having a planar surface. In this manner, planarizationlayer 32 is fabricated to possess a continuous, smooth, relativelydefect-free surface that may exhibit excellent adhesion to theimprinting layer 24.

[0038] Additionally, to ensure that imprinting layer 24 does not adhereto imprint device 14, surface 14 a may be treated with a modifyingagent. One such modifying agent is a release layer 34 formed from afluorocarbon silylating agent. Release layer 34 and other surfacemodifying agents, may be applied using any known process. For example,processing techniques that may include chemical vapor deposition method,physical vapor deposition, atomic layer deposition or various othertechniques, brazing and the like. In this configuration, imprintinglayer 24 is located between planarization layer 32 and release layer 34,during imprint lithography processes.

[0039] The embodiments of the present invention described above areexemplary. Many changes and modifications may be made to the disclosurerecited above, while remaining within the scope of the invention. Thescope of the invention should, therefore, be determined not withreference to the above description, but instead should be determinedwith reference to the appended claims along with their full scope ofequivalents.

What is claimed is:
 1. A composition polymerizable in response toradiation being incident thereupon, said composition comprising: a bisvinyl ether component; and an initiator component responsive to saidradiation to produce an acid in response thereto, with said bis vinylether component being reactive to said acid and polymerize in responsethereto.
 2. The composition as recited in claim 1 further including abase.
 3. The composition as recited in claim 1 wherein said bis vinylether component includes bis(vinyloxymethyl)dimethysilane.
 4. Thecomposition as recited in claim 1 wherein said bis vinyl ether componentincludes bis(divinyloxymethyl)tetramethyldisiloxane.
 5. The compositionas recited in claim 1 wherein said initiator component includestriphenylsulphonium salts and diphenyliodonium salts with the followingcounter-ions: antimony hexafluoride; phosphorus hexafluoride; borontetrafluoride; tris (trifluoromethylsulphonyl) methide.
 6. Thecomposition as recited in claim 1 wherein said bis vinyl ether componentfurther includes a mixture of a monomer acrylate and a vinyl componentselected from a set consisting of bis(vinyloxymethyl)dimethysilane andbis(divinyloxymethyl)tetramethyldisiloxane.
 7. The composition asrecited in claim 1 wherein said bis vinyl ether component isapproximately 98% of said composition and said initiator component isapproximately 2% of said composition.
 8. A method of patterning a layeron a substrate, said method comprising: forming a layer of polymerizablematerial on said substrate; contacting said layer of polymerizablematerial with a surface of a mold to conform said layer and said mold tosaid surface; partially polymerizing said layer by impinging radiationthereupon and terminating said radiation before polymerization of saidpolymerizable material is complete; separating said mold from said layerbefore complete polymerization of said layer occurs; and polymerizingsaid layer completely by allowing acid to react with said layer to forma solidified layer of said polymerizable material.
 9. The method asrecited in claim 8 wherein polymerizing said layer occurs in an absenceof said actinic radiation.
 10. The method as recited in claim 8 furtherincluding forming, before forming said layer of polymerizable material,a planarization layer adjacent to said substrate.
 11. The method asrecited in claim 8 further including providing said mold with a pattern,with contacting said layer of polymerizable material further includingforming said pattern in said layer of polymerizable material.
 12. Themethod as recited in claim 11 further including subjecting saidsolidified layer to an etching environment to transfer said pattern intosaid substrate.